Transpiration & Translocation - Organisation P2 Flashcards
What is transpiration?
Plants lose water to the air
What factors affect transpiration?
- Light intensity
- Temperature
- Air flow
- Humidity
How does high light intensity affect transpiration?
High light intensity -> more photosynthesis -> more gas exchange-> stomata opens -> more water loss
Why is transpiration less at night?
No photosynthesis means stomata is closed
What is used to measure the rate of transpiration?
Potometer
How do you find the rate of transpiration?
Distance moved by bubble ÷ time taken to move distance (s)
What is the transpiration stream?
Movement of water from the xylem to the leaves from the stomata
Explain the process of transpiration
- Root hair cells absorb water from soil
- Xylem transports water and mineral ions to other parts of the plant
- Water is lost by the stomata
How does humidity affect the rate of transpiration?
If the air is damp or humid, transpiration is limited.
More humid air - Slower transpiration
How does humidity affect the rate of transpiration?
If the air is damp or humid, transpiration is limited.
More humid air - Slower transpiration
What direction does the phloem transport substances?
Upwards and Downwards
What substances does the phloem transport?
Transports sucrose and amino acids
What substances does the xylem transport?
Transports water and minerals to parts
What is the vascular bundle?
Phloem and xylem tissue
What are sieve tubes in the phloem?
Specialised for transport and have no nucleas only cytoplasm
What are companian cells?
Transports substances in the phloem which requires energy - cells provide energy for that so it has lots of mitochondria
Examples of plant tissues
- Epidermal tissue
- Palisade mesophyll tissue
- Spongy mesophyll tissue
- Xylem and Phloem
- Meristem tissue
What does the epidermal tissue do?
Covered in waxy cuticle - prevents water loss by evaporation
What does the upper epidermis do?
Transparent so light can pass through it to the palisade layer
What does the palisade layer do?
Lots of chloroplasts, at the top so they get most light
What do the ai spaces in the spongy mesophyll do?
Increase rate of difusion in gases
What happens when plant has lots of water?
Gaurd cells go plump and turgid - makes stomata open so gases can be exchanged for photosynthesis
What happens when a plant lacks water?
Gaurd cells lose water and become flaccid - makes stomata close - stops water vapour from escaping
How are gaurd cells adapted?
- Sensitive to light
- Thin outer walls and thickened inner walls make the opening and closing work
- More stomata on undersides of leaves than on the top - lower surface is cooler and shadier so less water lost
